1. Field of the Invention
The present invention relates to a fire/smoke protection structure for a cable channel portion in a floor, a wall, or the like.
2. Description of the Related Art
A cable or pipe channel portion is formed in a floor or wall constituting a construction such as a building in order to dispose cables for supplying power or plastic pipes for supplying/exhausting water. In particular, a refractory material is filled in a channel portion within an area designated to be a fire partition. That is, if a fire occurs in a fire partition, a channel portion serves as a fire spreading port or flue to increase a damage caused by the fire. Therefore, a refractory material is filled in a channel portion to prevent this. Another reason for filling a refractory material in a channel portion is to prevent cables in the channel portion from being burned and to prevent the channel portion consisting of plastic pipes from being burned.
FIG. 1 is a sectional view showing a conventional fire/smoke protection structure for a cable channel portion in a floor. In FIG. 1, reference numeral 7 denotes a channel portion formed to extend through floor 4. Refractory material receiving metal piece 12 is inserted in channel portion 7 so as to cover the inner wall surface of channel portion 7. Metal piece 12 is fixed to floor 4 by fastening bolts 3. Opening portion 13 through which cables 5 are inserted is formed in metal piece 12. Refractory plate 14 is placed in opening portion 13 of metal piece 12. Cables 5 are inserted in opening portion 13 through plate 14. Plate 14 is formed of, e.g., a ceramic board. Fire retardant resin foaming body, e.g., foaming silicone 15 or the like is filled and foamed in a gap portion defined by metal piece 12, plate 14 and cables 5. An example of the foaming silicone used for this purpose is SEF-1900 (tradename) available from Furukawa Electric Co., Ltd.
In constructing the above conventional fire/smoke protection structure for a cable or pipe channel portion in a floor, filling of foaming silicone 15 at a site of construction presents various problems. That is, a twopart mixing type foaming silicone 15 is generally used. For this reason, substantially equal amounts of two solutions consisting of, e.g., A and B are uniformly mixed within a short time period of 30 to 60 seconds. This mixture must be filled in the above gap portion. In this case, as shown in FIG. 1, the foaming silicone mixture must be filled several times so that filling thicknesses a, b and c after foaming of the filled mixture are set to be 50 mm or less to provide a uniform foaming ratio.
In this case, however, a time for uniformly mixing equal amounts of two solutions A and B is too short. For this reason, a mixed state of the two solutions varies in accordance with a worker. In addition, a mixing time, a foaming time, and a foaming ratio depend on a temperature of two solutions A and B and an ambient temperature. Note that if the mixing time is increased, two solutions A and B are foamed and cured independently of each other in the form of layers a, b and c. This results in a low filling effect. In order to increase the mixing time, a foaming retarder is sometimes mixed in foaming silicone 15. In this case, however, foaming and curing at a low temperature become insufficient. In addition, a cell size in a foamed material is increased. Moreover, a foaming ratio is reduced.
Alternatively, two solutions A and B may be mixed by a mixing machine. However, it is troublesome to carry a mixer to a predetermined place of a building under construction. In addition, it is difficult to carry a mixer to a narrow construction place of a building.
In order to increase the number of cables, a cable channel portion in a floor once constructed is sometimes removed and then reconstructed. In this construction, the above problems are also posed with the above method when foaming silicone is filled.
FIG. 2 is a sectional view showing a conventional fire/smoke protection structure for a plastic pipe channel portion in a floor. In FIG. 2, the same reference numerals as in FIG. 1 denote the same parts. Refractory plate receiving metal piece 12 is inserted in channel portion 7 in floor 4. Refractory plate 14 consisting of a ceramic board is placed in metal piece 12. Plastic pipe 5' is inserted in opening portion 13 of metal piece 12 through plate 14. Mortar-like filler 6 is filled in a gap portion defined by metal piece 12, plate 14 and pipe 5'. Metal piece 12 is made of, e.g., iron. Filler 6 is formed of a refractory member such as gypsum, vermiculite and cement.
In filling filler 6 for constituting the fire/smoke protection structure for a cable channel portion in a floor, a predetermined amount of water is added to filler 6, mixed and agitated, and then filled in opening portion 13. A specific hydrating agent is sometimes used in accordance with the type of filler 6.
Generally, filler 6 must be thicker than floor 4. Especially when cables are to be inserted in opening portion 13, the thickness of filler 6 must be 200 to 300 mm because cables are good heat conductors.
However, the following problems are posed when filler 6 is constructed in a channel portion.
(1) A mixing ratio between water and filler 6 must be correctly set as determined.
(2) A long time period is required for curing filler 6.
(3) In particular, about a month is required for curing filler 6 in a cable channel portion. If cables move or vibrate in this period, a gap is formed between filler 6 and the cables. Therefore, a good fire/smoke protection structure cannot be obtained.
(4) After the number of pipes 5' or cables 5 is increased, filler 6 must be refilled. In this case, problems (1) to (3) are posed again.